1. Field of the Invention
The present invention relates to a method of multi-stage substrate etching and a terahertz oscillator manufactured using the same method, and more particularly to a method of multi-stage substrate etching which prevents a height deviation of an etching surface even in a deep step height, the curvature of an etching edge, and a T-shape of an etching wall face to thereby improve the etching quality, and a terahertz oscillator manufactured using the same method.
2. Description of the Prior Art
A terahertz bandwidth is very important in context with applications in molecular spectroscopy, biophysics, medicine, spectroscopy, video and security. Despite of its importance, it is true that the terahertz bandwidth (1012 Hz) ranged between the existing bandwidth of microwave and the optical frequency has almost no currently developed appliance, such as an oscillator or an amplifier, due to its mechanical, engineering limitation.
However, with the recent development in various new concepts and technology of micro machining, such an appliance has been actively developed. Together with the effort for increasing the frequency of the various oscillators in existing microwave bandwidth, many approaches have been tried to reduce the operating frequency to the terahertz bandwidth using an optical device such as semiconductor laser or femtosecond laser. Recently, many attempts have been proposed to provide a miniaturized terahertz radiation source.
Among them for providing a terahertz oscillator, it has been proposed a method of forming a 3-dimensional microstructure by providing a substrate with a plurality of steps using the MEMS technology. In particular, in order to form a plurality of steps in a substrate such as a silicon wafer, there is technology in which a plurality of mask patterns are deposited in series on the substrate, and the mask patterns are repeatedly removed through etching, thereby forming various step structures.
Meanwhile, there is another technology using the bonding of a wafer in which a protection layer is previously patterned to a first wafer, the first wafer is bonded to a second wafer, the second wafer is patterned and etched on its upper surface, and then the first wafer is etched in turn using the patterned protection layer.